Identification of Different Parts for a Three Phase Induction Motor (along with Function and Materials)

Experiment No.: 1

Experiment Name:

Identification of different parts (along with function and materials) for a given three phase induction motor.

Objective:

To identify (i) different parts (ii) function and (iii) materials of a three phase induction motor.

Theory:

The three phase induction motor is the most widely used electrical motor. Almost 80% of the mechanical power used by industries is provided by 3 ph induction motor because of its simple and rugged in construction, low cost, good operating characteristics. In three phase induction motor, the power is transferred from stator to rotor winding through induction. The induction motor is also called asynchronous motor as it runs at a speed other than the synchronous speed.

Stator Parts:

Sl. No.	Stator Parts	Position	Function	Materials
1.	Yoke	Outer part of Induction Motor	To hold the stator core and 3 phase windings	Cast iron
2.	Stator core	Fitted inner part of the yoke	To hold the windings	Laminated Silicon steel
3.	3 phase windings	3 different windings short pitched or full pitched and connected in star or delta connection	To produce uniform rotating magnetic field	Copper with Class B insulation
4.	Terminal Box	Mounted on the surface of the yoke	To cover the connecting terminals	Mild steel
6.	Name Plate	Reveted on the surface of yoke	To show the details of the motor, i.e. power in HP, voltage, full load current, full load speed in rpm, frequency, bearing number, duty cycle, insulation class, serial number, manufactures details etc.	Aluminium
7.	Cooling Fins	Casted with yoke	To increase the surface area of the yoke for cooling purpose by circulating air	Cast Iron
8.	End covers (Front & rear)	Fitted with yoke by bolt, on the front side and rear side of the motor	To hold the bearings and to protect the motor by covering the faces	Cast Iron
9.	Bearing housing	Casted with end covers or separately fitted	To hold the bearings	Cast Iron
10.	Bolts & Screwes	Fitting the loose parts of the motor	To fit the end covers and terminals box with yoke	Mild steel

Rotor Parts:

Sl. No.	Rotor Parts	Position	Function	Materials
1.	Shaft	Placed on the bearings	To couple mechanical load with the motor	Carbon steel
2.	Rotor core	Mounted on the Shaft	To hold the aluminium rotor bars and end rings	Laminted Silicon Steel
2.	Rotor aluminium bars	Fitted on the surface of the rotor core by skewing	To produce rotor emf, current and field. Behaves like a shorted secondary winding.	Aluminium
3.	Aluminium end rings	Mounted on two side of the core	To short the rotor bars and create a closed path for conducting the rotor current	Aluminium
4.	Bearings	Placed inside the bearing housing of stator end covers	To help the shaft for rotation of the rotor inside the stator by reducing the friction	Chrome Steel
5.	Fan	Fitted on the shaft	To cool the motor by forcing natural air.	Mild steel or Aluminium

Diagram:

Apparatus Used:

Sl No.	Name of Apparatus	Specification	Quantity	Makers name
1.	3 ph Squirrel Cage Induction Motor	1 HP, 415V, 50 Hz,1440 rpm	1	Tech-Track

Remarks: All parts of the three phase induction motor is dismantled and assembled successfully.